The generation of 15‐ps light pulses at 1.23 and 1.26 μm having 200 mW peak power at a repetition rate of up to 10 MHz from directly modulated unbiased V‐groove InxGa1−xAsyP1−y lasers is reported. Specially designed avalanche generators are employed for modulation of the laser injection current. The light pulses are analyzed using microstructured Gephotodetectors having a response of 62 ps at full width half‐maximum. A deconvolution technique based on a theoreticalanalysis of the complete circuit of the detection system is applied to reduce the large error occurring normally when the characteristics of fast pulses are determined from the response of much slower detectors. This technique is proved by independent experiments to hold. A spontaneous lifetime of 1.5 ns of the charge carriers in the active layer of the laser is determined from the measured delay times between the optical and electrical pulses.

Continuous lasing has been observed at 650 nm with a helium‐neon electrical discharge placed in an ultrahigh finesse optical cavity. This new lasing line is attributed to a Stokes–Raman process between the 1s5 and 1s4 electronic states of neon atoms pumped by the 632.8‐nm neon lasing line. A gain calculation based on a near‐resonant stimulated electronic Raman process predicts a lasing threshold for the 650‐nm line near that measured. Lasing output power was measured as a function of discharge current and helium‐neon gas pressure for the pump line and for the Stokes line.

Continuous‐wave (cw) operation at temperature up to 33 °C of an AlGaInP/GaInP mesa stripe laser has been achieved for the first time. The threshold current was 106 mA at 30 °C for a device with a mesa stripe 6 μm wide and 250 μm long. The emission wavelength was 678 nm under cw operation at 20 °C. The wafer, which was grown by atmospheric pressuremetalorganic chemical vapor deposition, had a dually stacked cladding structure in addition to a conventional double heterostructure. The mesa structure was formed by selective chemical etching of GaAs/AlGaAs over layers. The effect of the mesa structure on threshold current density, thermal resistance, and other characteristics was examined.

Thin‐film electroluminescent devices employing a new phosphor material ZnS:Sm,P have been found to exhibit bright red emission. Luminous efficiency of ZnS:Sm,P phosphorfilms is higher than that of ZnS:Sm phosphorfilms in the range of annealing temperature above 500 °C. A brightness of 1000 cd/m2 and an efficiency of 8×10−2 lm/W have been obtained in the devices with ZnS:Sm(1 at. %),P(0.5 at. %) phosphorfilmsannealed at 600 °C. These results indicate that P is an efficient co‐activator for Sm in ZnS.

The acceleration sensitivity of acoustic surface waveresonators (and delay lines) on quartz substrates supported uniformly at the base has been calculated. For normal acceleration the calculated sensitivity is almost two orders of magnitude lower than the lowest published measurements. For in‐plane acceleration the calculated sensitivity is comparable to the best published measurements. This causes us to believe that uniform base support has not been realized in practice and, in fact, may be impossible to achieve. For normal acceleration and nonuniform base support the calculations indicate that increasing the thickness of the substrate decreases the acceleration sensitivity. Experimental verification of this is presented. However, for in‐plane acceleration the calculations indicate that increasing the thickness of the substrate increases the acceleration sensitivity.

The ultrasonic waveforms generated by a pulsed laser incident at two positions on a steel plate are studied as a function of laser energy. At the 45° position there is a steady increase in compression wave amplitude with energy when passing from thermoelastic to ablation regimes, in contrast to the epicenter where there is a large increase in amplitude and change of pulse shape. It is concluded that the thermoelastic and ablation sources are comparable in generation efficiency per unit laser energy, except close to the epicenter, and that the chief effect of raising the power density is to vary the angular distribution of ultrasonicenergy.

Experimental measurements are presented of space and time integrated x‐ray emission from aluminumplasma produced by 2 ns (full width at half‐maximum), 268 nm Raman compressed KrF laser pulses. A single temperature spectrum was measured giving temperatures of 75–440 eV over the range of intensities 9×1011–2×1013 W/cm2. This scaling agrees well with a simple self‐regulating model. Conversion of laser energy into x rays above 1 keV energy was found to scale as I2.37L reaching 0.35% at 3.5×1013 W/cm2.

Optical emission spectroscopy was applied to study the rf glow discharge in hydrocarbons used for the deposition of amorphous hydrogenated carbon (a‐C:H). The optical data in conjunction with mass spectrometric measurements show that the species found in the glow region are very specific for the hydrocarbon used (e.g., benzene), but they are not directly related to the structure of the a‐C:H filmdeposited. In the vicinity of the negatively self‐biased cathode strong emission from CH is observed, irrespective of which hydrocarbon is used. The excited CH radicals are shown to result from fragmentation of the impacting hydrocarbon molecules. We conclude that this fragmentation upon impact is the key mechanism for the formation of hard a‐C:H, irrespective of the type of hydrocarbon used for the deposition.

Linear polydimethylsiloxanes (PDMS’s) are liquid polymers between 200 and 550 K and are well suited for experimental studies in fluid mechanics because (1) they are commercially available in a wide range of molecular lengths, (2) they are transparent and colorless, and (3) their flow behavior can be predicted from their molecular length. A particular PDMS can flow either as a viscous or strain rate softening fluid, depending upon its molecular length and the applied strain rate. Six different flow regimes are defined here to aid the selection of the appropriate PDMS for any particular experiment in fluid dynamics.Diffusion is sufficiently slow in PDMS’s of long molecular length so that finite strains can be visualized by the deformation of strain markers within it. This allows laboratory modeling of three‐dimensional strain histories in fluids which previously could only be approached by two‐dimensional numerical modeling.

Images of graphite have been recorded with a scanning tunneling microscope operating in air at ambient pressure. The results, which are in agreement with theory and previous experiments in vacuum, confirm that with a surface such as graphite the tunnelingmicroscopy in air can be used to examine the geometry of the surface with a resolution that is less than 2 Å.

It is shown that the energetically optimum shape of a precipitate which generates strains in the host lattice is a disc with a thickness that increases approximately with the square root of the size (disc radius). This relationship contravenes the two common assumptions that either the thickness or the aspect ratio stays unchanged during precipitate growth. From this relationship is derived a precipitate growth law of r∝t2/3. The results of the analysis are discussed with special reference to the growth of oxygen precipitates in silicon. The change in the morphology of oxygen precipitates with temperatures is also discussed.

Epitaxialcrystallization of Au‐implanted amorphous Si layers has been studied over the temperature range 515–735 °C. During crystallization,Au is zone refined into the remaining amorphous layer, resulting in an Au concentration that increases as the layer becomes thinner. The rate of solid phase epitaxy increases rapidly with Au concentration over the range from 0.15 to approximately 0.50 at. %. At higher concentrations the rate enhancement diminishes and above 0.70 at. % severe retardation of epitaxy is observed to occur.

A technique for stabilizing the ring‐shaped stripe domain has been developed for improving the Bloch line memory. Selective grooving in the magnetic film provides for both formation and stabilization of the ring domain. The inside wall of the ring domain is used for ring domain stabilization, through its grooved edge affinity. The outside wall of the domain is stabilized away from the grooved edge by the natural domain width. The following features are found. (1) The ring‐shaped domain is stable over a wide bias field range. (2) The demagnetizing field gradient, normal to the wall plane, can be kept almost the same at each position along the outside wall. (3) A stripe domain head can be formed controllably from a part of the ring‐shaped domain, as required in the Bloch line memory for stripe‐to‐bubble domain conversion.

Amorphousalloypowders of the types NiZr, CoZr, FeZr, and CuZr are produced by mechanical alloying from crystalline elemental powders. The alloying and amorphization process is monitored by microstructural investigations, x‐ray diffraction, and, where applicable, by magnetization measurements. The crystallizationtemperatures, determined by differential scanning calorimetry, are comparable to those measured for rapidly quenched and solid state reacted amorphous metals of the same compositions.

We have developed a phenomenological model for the photoconductivity in polycrystallinesemiconductors which takes into account the contributions from the majority carriers due to mobility enhancement in addition to the contributions due to photogenerated excess (minority) carriers. The model is applicable for the cases of both partially and completely depleted grains at all intensities of illumination. The model is compared with the experimental data of photoconductivity as a function of intensity of illumination obtained in polycrystallinesilicon at different temperatures. The data are in good agreement with the theoretical predictions. The results clearly demonstrate that in polycrystallinematerials,photoconductivity is a majority carrier phenomenon at low optical illuminations irrespective of whether the suppression of grain boundary potential barriers is partial or complete. However, at high level conditions, the photoconductivity behavior becomes an excess carrier effect as observed in single crystals.

Schottky barrierdiodes were used to detect and study hole defects in bulk‐grown p‐type GaAs by deep level transient spectroscopy. Several defects with concentrations of 1013–1016/cm3 were studied. It was found that two of these defects, with electronic levels at Ev +0.42 eV and Ev +0.58 eV, have electronic properties that closely correspond to those of Cu‐ and Fe‐related defects in GaAs. It is concluded that Schottky barrierdiodes on p‐GaAs can be very useful to detect and characterize typical metallic contaminants in GaAs.

A new technique is presented for separating the threshold‐voltage shift of a metal‐oxide‐semiconductor transistor into shifts due to interface traps and trapped‐oxide charge. This technique is applied to threshold‐voltage shifts on an n‐channel transistor that result from ionizing radiation.

A new technique has been developed to obtain the depth profile of trapped positive charge which has been introduced into the SiO2 layer in metal‐oxide‐silicon structures at low temperature. We use photon‐assisted tunneling at a fixed photon energy to inject electrons from the Si into the SiO2. Trapped positive charge located closer to the interface than the point at which the electrons emerge into the oxide conduction band is not affected, while that farther away can capture electrons. From the shifts of the capacitance versus voltage curves at various biases we can profile the location of the trapped positive charge. We demonstrate the use of this technique with a comparison of the positive charge introduced by x irradiation and Fowler–Nordheim tunneling (high‐field stress). For the x‐ray irradiated samples, the positive charge is located considerably farther (20–35 Å) from the Si‐SiO2interface than for high‐field stressed samples (<20 Å).

We report, for the first time, temperature‐dependent Hall data for holes in modulation‐doped In0.2Ga0.8As/GaAs strained‐layer superlattices. Samples with (compressive) planar strains of −0.5% to −1.2% in the InGaAs quantum wells were used, providing a range of configurations for the two (overlapping) sets of valence‐band quantum wells derived from the bulk heavy‐ and light‐hole bands. All samples exhibit transfer of holes into the InGaAs quantum wells at low temperature; however, the sample with the least strain shows evidence for gradual carrier freeze‐out over a wide range of temperature.